Limited depth penetration needle housing

ABSTRACT

Disclosed are methods and means for facilitating injection which enable a correct penetration depth of the needle. These improvements are obtainable by using a needle covering device comprising an axially displaceable first tubular sleeve (30) arranged around the front part of said injection apparatus which at its foremost part surrounds the needle (11) over its entire length, and while overcoming a spring force, is axially displaceable rearwards to expose a predetermined length of the needle, said device further comprises a stationary outer tubular sleeve (40) releasably attached to the injection apparatus and fitted around the front part of said injection apparatus and an inner adjustable tubular stopping sleeve (20) which is axially displaceable between at least two predetermined positions while performing a sliding, helical motion around said front part of said injection apparatus when setting the distance between the foremost part of said stopping sleeve and a stopping flange (31) arranged on the inside of the axially displaceable first sleeve.

The present invention is related to facilitating injection, especiallysubcutaneous injection by providing a means and methods which enable acorrect penetration depth of the needle and thereby to achieve a correcttherapeutical effect from the injected drug even if the injection siteis altered by the patient.

It is highly desirable for a manufacturer and supplier ofpharmaceuticals to meet the demands from patients who are confined to along time regimen of administration by self-injections. Such patentsrequire safe and convenient equipment which to the highest possibleextent will liberate them from the burden of repeated drug taking byinjections. It must also be considered that many such patients areelderly or of infant age and might have a reduced physical strength anda strong aversion of needles. Many attempts have therefore been made toprovide injection devices which hide or cover the needle for the userand only exposes it at the moment of administration. These devices alsohave also the advantage that they cover the needle from inadvertentcontamination before administration and also provide safety fromaccidental needle sticks from a used needle. Another requirement ofself-injections is that they must be repeatable in order to provide thepatient with a correct dose of the pharmaceutical. Since thebioabsorption may vary considerably for a given drug depending on thewhether it is administered subcutaneously or intramuscularly, it is ofhigh importance to have a fixed penetration depth of the needle forrepeated injections. An inaccurate injection depth may even in certainapplications lead to varied effect of the drug which for example for adiabetic dependent on insulin might have fatal consequences.

A means which can be used on an injection device for limiting thepenetration of the needle which also entirely covers the needle for theuser is disclosed in the International patent applicationPCT/SE92/00596. With this needle cover it is, however, not possible toadjust the penetration depth of the needle, which is a drawbackespecially when it is desired to inject the drug into the subcutaneousfat layer. A penetration depth adjustment is especially advantageouswhen injecting drugs subcutaneously, because the subcutaneous fat layernot only varies considerably between individual patients, it also variesbetween different parts of an individual body, for example between thethigh, the abdominal area, the arms and the legs. For many drugs,especially polypeptides or proteins like insulin, factor VIII and humangrowth hormone, also the bioabsorption may vary considerably betweenintramuscular and subcutaneous administration and also many timeslocally between different subcutaneous injection sites. In addition,many such drugs might demonstrate an improved activity when administeredsubcutaneously such as the factor VIII-preparations disclosed in theInternational patent applications WO 95/01804 and PCT/SE95/00348.

It would therefore be a significant improvement in convenience andsafety for many patients to obtain an injection device which can givethem a higher freedom to select and alter the injection site, whileretaining a correct injection depth for each administration so arepeated drug effect is maintained.

It would also be an improvement to be able to benefit from theadvantages of subcutaneous administration and be able to freely selectsubcutaneous injection sites based on individual desire.

An object of the present invention is to provide a device whichmaintains all the advantages of a needle covering device while alsomaking it possible to readily adjust the needle penetration depthbetween different pre-set values. This object is attained by the needlecovering device as defined herein.

It is also an object of the present invention to provide a method ofadjusting the penetration depth of the needle of an injection apparatus.

Another object of the present invention is to provide an improved methodof administering a drug by subcutaneous injection so that a correctpenetration depth of the injection needle in the subcutaneous fat layerof patient always is obtained.

A further object of the invention is to provide a kit for subcutaneousinjection comprising an injection apparatus and a tubular needlecovering device attachable thereto, by means of which a correctsubcutaneous injection can be obtained irrespective of the injectionsite.

A preferred embodiment of the present invention is now described indetail with reference to the appended drawings.

FIG. 1 shows a needle covering device providing a pre-set penetrationdepth, according to the present invention, before administration.

FIG. 2 shows the device according to FIG. 1 during the administrationwith a first shorter penetration depth of the needle.

FIG. 3 shows the device according to FIG. 1 with a second longerpenetration depth of the needle.

FIG. 4 shows a cross-section of the device according to FIG. 3 in thedirection A--A.

FIG. 5 shows a side view of a needle covering device according to thepresent invention in a natural size.

FIG. 1 shows a front end of an injection apparatus 10 having a needle 11attached to its foremost end with a needle attachment device of aconventional design, providing that the needle is in liquidcommunication with the subcutaneously injectible drug. The injectionapparatus may be a conventional single dose syringe or an injection pencontaining multiple doses connected to a dosing device. The injectionapparatus as such is not a part of the present invention and a widevariety of such devices are understood to be possible to use with thepresent invention if they are provided with suitable attachment means toan adjustable needle covering apparatus according to the invention. Inthe arrangement of FIG. 1, the injection apparatus is attached to anouter stationary tubular sleeve with a releasable attachment device (notshown) which preferably is snap-lock device of a conventional type.Other types of attachment devices are well-known to the skilled personand will not be discussed in further detail. The outer tubular sleeve 40is connected to a first axially displaceable sleeve 30 which in FIG. 1is in its foremost position with a flange 33, resting on a shoulder part43 of stationary sleeve 40. In this position, the first tubular sleeve30 covers the needle entirely. Furthermore, the needle covering devicecomprises an inner adjustable stopping sleeve 20 having a slotted frontpart through which the needle and its attachment device extends, saidfront part also is provided with protruding stopping means 24 whichco-operates with stopping flange 31 on the inside of sleeve 30 wherebylimiting the penetration depth of needle during injection. Between aflange part 32 inside the axially displaceable sleeve 30 and a shoulderpart 22 of the stopping sleeve 20 a helical spring device 50 is extendedwhich surrounds the front part of the injection apparatus. The springdevice has a spring force which must be overcome by the user whenpressing the needle covering device against the injection site in orderto obtain a subcutaneous penetration of the needle. It is preferable todesign the needle covering device so a major part of the helical springdevice (50) is in a position rear of the point (13) where the needleprotrudes from the attachment device (12) at the moment of injection.Such a design causes a major part of the needle to be used for theinjection and a more comfortable administration for the patient isachieved. At the rear end of the stopping device, diametrically oppositeprotrusions 21, 21' extend through correspondent slits in the outerstationary sleeve. These features will be explained in more detailbelow.

To administer a dose from the injection apparatus the needle coveringdevice is pressed gently against the injection site and then byovercoming the spring force of the spring device 50, the stopping device24 will meet the stopping flange 31, while the needle is forced outthrough the aperture 34 of the sleeve 30 for a predetermined distanceidentical to the set distance between said device 24 and flange 31 inresting position, see FIG. 2. After actuating the injection apparatus ina conventional manner to expel and administer a given drug quantity, thespring force can return the needle cover device to the position shown inFIG. 1.

A new penetration depth can be set by axially displacing the stoppingsleeve 40 between its predetermined positions while it performs asliding helical motion around the front part of the injection apparatusso a new distance between the foremost part of the stopping sleeve andthe stopping flange 31 arranged on the inside of the axiallydisplaceable first sleeve 30, is achieved. The foremost part of thestopping sleeve is preferably an annular stopping flange 24 which hitsthe preferably annular stopping flange 31 in the stopping position. Asbest seen in FIG. 5, the setting of a new penetration depth is performedby moving diametrically opposite protrusions 21, 21' of the stoppingsleeve simultaneously in the slits 41, 42 and the diametrically oppositeslits 41',42', not shown in FIG. 5, of the outer stationary sleeve 40,wherein said protrusions are slidingly fitted, see also FIG. 4 which isa cross-sectional view through the slits. When selecting the longerpenetration depth of the needle, as demonstrated in FIG. 3, theprotrusions 21, 21' are slidingly moved from the slits 42, 42' to theslits 41, 41' while the stopping sleeve performs helical motion aroundthe injection apparatus. It is to be understood that more slits thandemonstrated in FIG. 5 can be used, in order to obtain more than twopredetermined penetration depths of the needle. The arrangement withdiametrically opposite slits and protrusions shall be regarded as apreferred embodiment of the present invention. The form and number ofprotrusion and slits may be varied within the scope of the invention toobtain the desired penetration depths that will fit a certaintherapeutical application.

Also there are other ways of axially displacing a stopping sleevebetween predetermined positions to fix the axial distance between itsforemost part and an axially displaceable spring loaded needle coveringfirst sleeve to obtain corresponding pre-set penetration depths into thesubcutaneous fat layer. The injection needle of an injection apparatuscan be connected to said sleeves by means other than said protrusionsand slits and these are also part of the present invention.

In many applications it is advantageous to provide the injectionapparatus to the user without the needle attached thereto in the form ofa ready-to-use kit together with the needle cover device. The patientcan readily attach the needle cover device to the injection apparatusafter removing a temporary needle protecting device and can adjust theneedle cover to a certain desired injection depth that corresponds to asubcutaneous injection site. It is preferred that the patient selectssuitable penetration depths corresponding to selected subcutaneousinjection sites after discussion with a physician, since the depth ofthe subcutaneous fat layer varies between different individuals.

The adjustable needle cover device of the present invention shall not beregarded as limited for subcutaneous administration, since it can bemade equally useful for other forms of administration by injection.

We claim:
 1. A needle device for adjusting a penetration depth of aneedle connected to an injection apparatus, comprising:an injectionapparatus comprising a needle axially protruding from a front partthereof; an axially displaceable first tubular sleeve arranged around afront part of said injection apparatus, wherein said sleeve comprises aforemost part that surrounds the needle over its entire length; acompression spring disposed within said foremost part of said firsttubular sleeve adapted to be in compressive relationship with said frontpart of said injection device; wherein said injection apparatus and saidtubular sleeve are axially displaceable with respect to each other andare adapted, by said axial displacement, to expose a predeterminedlength of needle through said foremost part of said first tubularsleeve; an outer tubular sleeve releasably attached to, and stationarywith respect to, the injection apparatus disposed around at least aportion of the front part of said injection apparatus; and an adjustableinner tubular stopping sleeve axially displaceable between at least twopredetermined positions with respect to said front part of saidinjection apparatus; and a stopping surface arranged on the inside ofthe axially displaceable first sleeve and adapted to engage with saidinner adjustable tubular stopping sleeve; whereby said axialdisplacement sets different distances between the foremost part of saidstopping sleeve and said stopping surface, and thereby sets differentneedle length protrusions from the front of said first tubular sleeve.2. A device according to claim 1, wherein said spring is a helicalspring.
 3. A device according to claim 2, wherein said helical springextends between a shoulder part of the stopping sleeve and an inwardlydirected flange of first sleeve.
 4. A device according to claim 2wherein when said inner tubular stopping sleeve engages with saidstopping surface, a major part of the helical spring is disposedrearwardly of the point where the needle protrudes.
 5. A deviceaccording to claim 1 wherein the stationary outer sleeve has at leasttwo radially extended slits, wherein said stopping sleeve has at leastone protrusion that is adapted to engage with said slits, and whereinsaid slits are disposed in an axially spaced relationship wherebyengagement of said protrusion with each of said slits permits saidneedle to protrude a different distance.
 6. A method of adjusting apenetration depth of a needle of an injection apparatus, which apparatuscomprises:an axially moveable injection apparatus, comprising an axiallydisposed needle, surrounded by a first tubular sleeve; an inner stoppingsleeve, comprising a foremost part, connected to said first tubularsleeve; an outer stationary sleeve connected to said first tubularsleeve; and a stopping surface disposed inside the first tubular sleeveand adapted to engage said foremost part of said stopping sleeve;whereinsaid method comprises: helically moving said stopping sleeve between atleast two predetermined positions around a front part of said injectionapparatus; and thereby setting a distance between the foremost part ofsaid stopping sleeve and said stopping surface which distancecorresponds to a selected needle penetration depth.
 7. A methodaccording to claim 6, further comprising:engaging said stopping sleevewith the stationary sleeve by fitting at least one protrusion on saidstopping sleeve with radially arranged axially spaced slits on saidfirst tubular sleeve; and slidingly moving said sleeves relative to eachother.